Shunt device and method for treating glaucoma

ABSTRACT

Shunt devices and a method for continuously decompressing elevated intraocular pressure in eyes affected by glaucoma by diverting excess aqueous humor from the anterior chamber of the eye into Schlemm&#39;s canal where post-operative patency can be maintained with an indwelling shunt device which surgically connects the canal with the anterior chamber. The shunt devices provide uni- or bi-directional flow of aqueous humor into Schlemm&#39;s canal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/445,740, filed May 27, 2003 now U.S. Pat. No. 6,827,700, which is acontinuation of U.S. patent application Ser. No. 10/242,385, filed Sep.12, 2002 now U.S. Pat. No. 6,626,858, which is a continuation of U.S.patent Ser. No. 09/558,505, filed Apr. 26, 2000, now U.S. Pat. No.6,450,984, which claims the benefit of U.S. Provisional Application No.60/131,030, filed Apr. 26, 1999.

GOVERNMENT LICENSE

The U.S. Government has reserved a nonexclusive, irrevocable,royalty-free license in the invention with power to grant licenses forall governmental purposes.

TECHNICAL FIELD

The present invention is generally directed to a surgical treatment forglaucoma, and relates more particularly to a device and method forcontinuously decompressing elevated intraocular pressure in eyesaffected by glaucoma by diverting aqueous humor from the anteriorchamber of the eye into Schlemm's canal where post-operative patency canbe maintained with an indwelling shunt which can be surgically placed toconnect the canal with the anterior chamber.

BACKGROUND OF THE INVENTION

Glaucoma is a significant public health problem, because glaucoma is amajor cause of blindness. The blindness that results from glaucomainvolves both central and peripheral vision and has a major impact on anindividual's ability to lead an independent life.

Glaucoma is an optic neuropathy (a disorder of the optic nerve) thatusually occurs in the setting of an elevated intraocular pressure. Thepressure within the eye increases and this is associated with changes inthe appearance (“cupping”) and function (“blind spots” in the visualfield) of the optic nerve. If the pressure remains high enough for along enough period of time, total vision loss occurs. High pressuredevelops in an eye because of an internal fluid imbalance.

The eye is a hollow structure that contains a clear fluid called“aqueous humor.” Aqueous humor is formed in the posterior chamber of theeye by the ciliary body at a rate of about 2.5 microliters per minute.The fluid, which is made at a fairly constant rate, then passes aroundthe lens, through the pupillary opening in the iris and into theanterior chamber of the eye. Once in the anterior chamber, the fluiddrains out of the eye through two different routes. In the “uveoscleral”route, the fluid percolates between muscle fibers of the ciliary body.This route accounts for approximately ten percent of the aqueous outflowin humans. The primary pathway for aqueous outflow in humans is throughthe “canalicular” route that involves the trabecular meshwork andSchlemm's canal.

The trabecular meshwork and Schlemm's canal are located at the junctionbetween the iris and the sclera. This junction or corner is called “theangle.” The trabecular meshwork is a wedge-shaped structure that runsaround the circumference of the eye. It is composed of collagen beamsarranged in a three-dimensional sieve-like structure. The beams arelined with a monolayer of cells called trabecular cells. The spacesbetween the collagen beams are filled with an extracellular substancethat is produced by the trabecular cells. These cells also produceenzymes that degrade the extracellular material. Schlemm's canal isadjacent to the trabecular meshwork. The outer wall of the trabecularmeshwork coincides with the inner wall of Schlemm's canal. Schlemm'scanal is a tube-like structure that runs around the circumference of thecornea. In human adults, Schlemm's Canal is believed to be divided bysepta into a series of autonomous, dead-end canals.

The aqueous fluid travels through the spaces between the trabecularbeams, across the inner wall of Schlemm's canal into the canal, througha series of about 25 collecting channels that drain from Schlemm's canaland into the episcleral venous system. In a normal situation, aqueousproduction is equal to aqueous outflow and intraocular pressure remainsfairly constant in the 15 to 21 mmHg range. In glaucoma, the resistancethrough the canalicular outflow system is abnormally high.

In primary open angle glaucoma, which is the most common form ofglaucoma, the abnormal resistance is believed to be along the outeraspect of trabecular meshwork and the inner wall of Schlemm's canal. Itis believed that an abnormal metabolism of the trabecular cells leads toan excessive build up of extracellular materials or a build up ofabnormally “stiff” materials in this area. Primary open angle glaucomaaccounts for approximately eighty-five percent of all glaucoma. Otherforms of glaucoma (such as angle closure glaucoma and secondaryglaucomas) also involve decreased outflow through the canalicularpathway but the increased resistance is from other causes such asmechanical blockage, inflammatory debris, cellular blockage, etc.

With the increased resistance, the aqueous fluid builds up because itcannot exit fast enough. As the fluid builds up, the intraocularpressure (IOP) within the eye increases. The increased IOP compressesthe axons in the optic nerve and also may compromise the vascular supplyto the optic nerve. The optic nerve carries vision from the eye to thebrain. Some optic nerves seem more susceptible to IOP than other eyes.While research is investigating ways to protect the nerve from anelevated pressure, the only therapeutic approach currently available inglaucoma is to reduce the intraocular pressure.

The clinical treatment of glaucoma is approached in a step-wise fashion.Medication often is the first treatment option. Administered eithertopically or orally, these medications work to either reduce aqueousproduction or they act to increase outflow. Currently availablemedications have many serious side effects including: congestive heartfailure, respiratory distress, hypertension, depression, renal stones,aplastic anemia, sexual dysfunction and death. Compliance withmedication is a major problem, with estimates that over half of glaucomapatients do not follow their correct dosing schedules.

When medication fails to adequately reduce the pressure, lasertrabeculoplasty often is performed. In laser trabeculoplasty, thermalenergy from a laser is applied to a number of noncontiguous spots in thetrabecular meshwork. It is believed that the laser energy stimulates themetabolism of the trabecular cells in some way, and changes theextracellular material in the trabecular meshwork. In approximatelyeighty percent of patients, aqueous outflow is enhanced and IOPdecreases. However, the effect often is not long lasting and fiftypercent of patients develop an elevated pressure within five years. Thelaser surgery is not usually repeatable. In addition, lasertrabeculoplasty is not an effective treatment for primary open angleglaucoma in patients less than fifty years of age, nor is it effectivefor angle closure glaucoma and many secondary glaucomas.

If laser trabeculoplasty does not reduce the pressure enough, thenfiltering surgery is performed. With filtering surgery, a hole is madein the sclera and angle region. This hole allows the aqueous fluid toleave the eye through an alternate route.

The most commonly performed filtering procedure is a trabeculectomy. Ina trabeculectomy, a posterior incision is made in the conjunctiva, thetransparent tissue that covers the sclera. The conjunctiva is rolledforward, exposing the sclera at the limbus. A partial thickness scleralflap is made and dissected half-thickness into the cornea. The anteriorchamber is entered beneath the scleral flap and a section of deep scleraand trabecular meshwork is excised. The scleral flap is loosely sewnback into place. The conjunctival incision is tightly closed.Post-operatively, the aqueous fluid passes through the hole, beneath thescleral flap and collects in an elevated space beneath the conjunctiva.The fluid then is either absorbed through blood vessels in theconjunctiva or traverses across the conjunctiva into the tear film.

Trabeculectomy is associated with many problems. Fibroblasts that arepresent in the episclera proliferate and migrate and can scar down thescleral flap. Failure from scarring may occur, particularly in childrenand young adults. Of eyes that have an initially successfultrabeculectomy, eighty percent will fail from scarring within three tofive years after surgery. To minimize fibrosis, surgeons now areapplying antifibrotic agents such as mitomycin C (MMC) and5-fluorouracil (5-FU) to the scleral flap at the time of surgery. Theuse of these agents has increased the success rate of trabeculectomy butalso has increased the prevalence of hypotony. Hypotony is a problemthat develops when aqueous flows out of the eye too fast. The eyepressure drops too low (usually less than 6.0 mmHg); the structure ofthe eye collapses and vision decreases.

Trabeculectomy creates a pathway for aqueous fluid to escape to thesurface of the eye. At the same time, it creates a pathway for bacteriathat normally live on the surface of the eye and eyelids to get into theeye. If this happens, an internal eye infection can occur calledendophthalmitis. Endophthalmitis often leads to permanent and profoundvisual loss. Endophthalmitis can occur anytime after trabeculectomy. Therisk increases with the thin blobs that develop after MMC and 5-FU.Another factor that contributes to infection is the placement of a bleb.Eyes that have trabeculectomy performed inferiorly have about five timesthe risk of eye infection than eyes that have a superior bleb.Therefore, initial trabeculectomy is performed superiorly under theeyelid, in either the nasal or temporal quadrant.

In addition to scarring, hypotony and infection, there are othercomplications of trabeculectomy. The bleb can tear and lead to profoundhypotony. The bleb can be irritating and can disrupt the normal tearfilm, leading to blurred vision. Patients with blebs generally cannotwear contact lenses. All of the complications from trabeculectomy stemfrom the fact that fluid is being diverted from inside the eye to theexternal surface of the eye.

When trabeculectomy doesn't successfully lower the eye pressure, thenext surgical step often is an aqueous shunt device. An aqueousdiversion device of the prior art is a silicone tube that is attached atone end to a plastic (polypropylene or other synthetic) plate. With anaqueous shunt device, an incision is made in the conjunctiva, exposingthe sclera. The plastic plate is sewn to the surface of the eyeposteriorly, usually over the equator. A full thickness hole is madeinto the eye at the limbus, usually with a needle. The tube is insertedinto the eye through this hole. The external portion of the tube iscovered with either donor sclera or pericardium. The conjunctiva isreplaced and the incision is closed tightly.

With prior art aqueous diversion devices, aqueous drains out of the eyethrough the silicone tube to the surface of the eye. Deeper orbitaltissues then absorb the fluid. The outside end of the tube is protectedfrom fibroblasts and scarring by the plastic plate. Many complicationsare associated with aqueous shunt devices. A thickened wall of scartissue that develops around the plastic plate offers some resistance tooutflow and in many eyes limits the reduction in eye pressure. In someeyes, hypotony develops because the flow through the tube is notrestricted. Many physicians tie an absorbable suture around the tube andwait for the suture to dissolve post-operatively at which time enoughscar tissue has hopefully formed around the plate. Some devices containa pressure-sensitive valve within the tube, although these valves maynot function properly. The surgery involves operating in the posteriororbit and many patients develop an eye muscle imbalance and doublevision post-operatively. With prior art aqueous shunt devices, a pathwayis created for bacteria to get into the eye and endophthalmitis canpotentially occur.

The prior art includes a number of such aqueous shunt devices, such asU.S. Pat. No. 4,936,825 (providing a tubular shunt from the anteriorchamber to the corneal surface for the treatment of glaucoma), U.S. Pat.No. 5,127,901 (directed to a transscleral shunt from the anteriorchamber to the subconjunctival space), U.S. Pat. No. 5,180,362 (teachinga helical steel implant that is placed to provide drainage from theanterior chamber to the subconjunctival space), and U.S. Pat. No.5,433,701 (generally teaching shunting from the anterior chamber to thescleral or conjunctival spaces).

In addition to the prior art aqueous shunt devices described above,other prior art devices for glaucoma surgery have used setons, or otherporous, wick-like components to divert and convey excess aqueous fromthe anterior chamber to the exterior ocular surface. Examples includeU.S. Pat. Nos. 4,634,418 and 4,787,885 (teaching the surgical treatmentof glaucoma using an implant that consists of a triangular seton(wick)), and U.S. Pat. No. 4,946,436, (teaching the use of a porousdevice to shunt anterior chamber to subscleral space). These patents donot teach placement in Schlemm's canal.

Some prior art references for glaucoma management have been directed atSchlemm's canal, but these have not involved the placement of long-term,indwelling shunts. U.S. Pat. No. 5,360,399 teaches the temporaryplacement of a plastic or steel tube with preformed curvature inSchlemm's canal with injection of a viscous material through the tube tohydraulically expand and hydrodissect the trabecular meshwork. The tubeis removed from the canal following injection. Because the tube isdirected outwardly from the eye for injection access, the intersectionof the outflow element with the preformed curved element withinSchlemm's canal is at about a 90 degree angle relative to the plane ofthe curvature, and 180 degrees away from the anterior chamber.Therefore, at no time does any portion of the '399 device communicatewith the anterior chamber. Furthermore, relative to that portion withinSchlemm's canal, this tube has a larger diameter injection cuff element,which serves as an adapter for irrigation. Therefore, this device is notadapted for shunting aqueous between the anterior chamber and Schlemm'scanal.

Most of the problems that have developed with current glaucoma treatmentdevices and procedures have occurred because aqueous fluid is drainedfrom inside of the eye to the surface of the eye. A need exists, then,for a more physiologic system to enhance the drainage of aqueous fluidfrom the anterior chamber into Schlemm's canal. In the vast majority ofglaucoma patients, the resistance problem lies between Schlemm's canaland the anterior chamber. The canal itself, the collecting channels andthe episcleral venous system all are intact. Enhancing aqueous flowdirectly into Schlemm's canal would minimize the scarring that usuallyoccurs with external filtration procedure since the internal angleregion is populated with a single line of nonproliferating trabecularcells. Enhancing aqueous flow directly into Schlemm's canal wouldminimize hypotony since the canal is part of the normal outflow systemand is biologically engineered to handle the normal volume of aqueoushumor. Enhancing aqueous flow directly into Schlemm's canal wouldeliminate complications such as endophthalmitis and leaks.

SUMMARY OF THE INVENTION

The present invention is directed to a novel shunt and an associatedsurgical method for the treatment of glaucoma in which the shunt isplaced to divert aqueous humor from the anterior chamber of the eye intoSchlemm's canal. The present invention therefore facilitates the normalphysiologic pathway for drainage of aqueous humor from the anteriorchamber, rather than shunting to the sclera or another anatomic site asis done in most prior art shunt devices. The present invention isfurther directed to providing a permanent, indwelling shunt to provideincreased egress of aqueous humor from the anterior chamber to Schlemm'scanal for glaucoma management.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is an illustration showing an overhead perspective view of oneembodiment of the present invention, in which the inventive shunt iscomprised of tubular elements extending bi-directionally withinSchlemm's canal.

FIG. 1B is an overhead view of the embodiment of the present inventionshown in FIG. 1A, with phantom lines detailing the internalcommunication between the lumens of the tubular elements comprising theinventive device.

FIG. 1C is an illustration showing an overhead perspective view of oneembodiment of the present invention, in which the inventive shunt iscomprised of mesh tubular elements extending bi-directionally withinSchlemm's canal.

FIG. 1D is an illustration showing an overhead perspective view of oneembodiment of the present invention, in which the inventive shunt iscomprised of solid, porous elements extending bi-directionally withinSchlemm's canal.

FIG. 1E is an overhead perspective view of another embodiment of thepresent invention, with phantom lines detailing the internalcommunication between the two proximal lumens and the single distallumen of the inventive device.

FIG. 2 is an illustration showing another embodiment of the presentinvention, in which the inventive shunt is comprised of perforatedtubular elements and with an angulated terminal aspect of the proximalportion.

FIG. 3A is an illustration showing a perspective of another embodimentof the present invention in which the inventive shunt is comprised ofelements that are partially tubular and partially open in theirconfiguration.

FIG. 3B is an illustration showing a top view of the embodiment of thepresent invention in FIG. 3A, with phantom lines detailing the internalcommunication of the device.

FIG. 3C is an illustration showing a side view from the proximal end ofthe embodiment of the present invention in FIG. 3A.

FIG. 3D is an illustration showing a perspective of another embodimentof the present invention in which the inventive shunt is comprised ofelements that are partially open and trough-like in their configuration.

FIG. 4 is an illustration showing another embodiment of the presentinvention, in which the inventive shunt is comprised of distal elementshaving wicking extensions at their terminal ends, and in which theproximal portion has a sealed, blunted tip with a portal continuous withthe lumen of the proximal portion, oriented to face away from the iriswhen the device is implanted in Schlemm's canal.

FIG. 5A is an illustration showing another embodiment of the inventiveshunt in which a portion of the device enters Schlemm's canal in onlyone direction and shunts fluid in a non-linear path from the anteriorchamber.

FIG. 5B is an illustration showing an alternative embodiment of theinventive shunt in which the entire shunt is placed within Schlemm'scanal but contains a fenestration to maintain fluid egress of aqueoushumor from the anterior chamber to Schlemm's canal.

FIG. 5C is an illustration showing a side view of one embodiment of thepresent invention, in which the inventive shunt is comprised of tubularelements, with a proximal portion extending towards the anterior chamberthat is shorter relative to the distal portions which extendbi-directionally within Schlemm's canal.

FIG. 5D is an illustration showing an alternative embodiment of theinventive shunt comprised of a partially open trough-like element whichis placed within Schlemm's canal but contains a portal to maintain fluidegress of aqueous humor from the anterior chamber to Schlemm's canal.

FIG. 5E is an illustration showing an alternative embodiment of theinventive shunt comprised of a solid, but porous wick-like element whichis placed within Schlemm's canal.

FIG. 6A is an illustration showing certain anatomic details of the humaneye.

FIG. 6B is a cross-sectional illustration showing the anatomicrelationships of the surgical placement of an exemplary embodiment ofthe present invention.

FIG. 6C is a cross-sectional illustration showing the anatomicrelationships of the surgical placement of another exemplary embodimentof the present invention in which the proximal portion has an angulatedterminal aspect with a sealed, blunted tip with a portal continuous withthe lumen of the proximal portion, oriented to face away from the iriswhen the device is implanted in Schlemm's canal.

DETAILED DESCRIPTION OF PRESENT INVENTION

The present invention provides an aqueous humor shunt device to divertaqueous humor in the eye from the anterior chamber into Schlemm's canal,in which the shunt device comprises a distal portion having at least oneterminal aspect sized and shaped to be circumferentially received withina portion of Schlemm's canal, and a proximal portion having at least oneterminal aspect sized and shaped to be received within the anteriorchamber of the eye, wherein the device permits fluid communicationbetween the proximal portion in the anterior chamber to the distalportion in Schlemm's canal. Fluid communication can be facilitated by anaqueous humor directing channel in either the proximal or distalportions, as described below. Fluid communication can also befacilitated by a wicking function of a solid proximal or distal portionsof the device, for example.

The present invention also provides embodiments of an inventive shuntcomprising a body of biocompatible material of a size and shape adaptedto be at least partially circumferentially received within a portion ofSchlemm's canal to divert aqueous humor from the anterior chamber of thehuman eye to and within Schlemm's canal, and wherein the bodyfacilitates the passage of aqueous humor from the anterior chamber intoSchlemm's canal. This embodiment of the device of the present inventioncan be produced without the proximal portion of the previous embodimentextending into the anterior chamber. An aqueous humor directing channelcan facilitate the passage of aqueous humor from the anterior chamberinto Schlemm's canal. Fluid communication can also be facilitated by awicking function of a solid body portion, for example.

The invention contemplates many different configurations for an aqueoushumor directing channel, provided that each assists in channelingaqueous humor from the anterior chamber to Schlemm's canal, such as byproviding a lumen, trough, wick or capillary action. For example, theaqueous humor directing channel can be a fully enclosed lumen, apartially enclosed lumen, or a trough-like channel that is at leastpartially open. The invention contemplates that a solid monofilament orbraided polymer, such as proline, can be inserted into Schlemm's canalto provide a wicking function to facilitate the passage of aqueous humorfrom the anterior chamber to Schlemm's canal. Such a wicking extensioncan also be grooved or fluted along any portion of the length thereof,so as to be multi-angular or star-shaped in cross-section. The devicesof the present invention can be constructed of a solid, matrix, mesh,fenestrated, or porous material, or combinations thereof.

Traditional glaucoma teaching states that Schlemm's canal in an adult isdivided by septa into separate canals, rendering the complete passage ofa suture impossible. Preliminary studies on adult human eye bank eyeshave shown that Schlemm's canal is, indeed, patent. A suture can bepassed through the entire circumference of the canal. It has not beenheretofore determined that Schlemm's canal is patent throughout itscircumference in normal adult individuals, as opposed to being dividedby septae into multiple dead end canals. The invention utilizes thisknowledge to access Schlemm's canal and to create and maintain thenatural physiologic egress of aqueous humor from the anterior chamber toSchlemm's canal and to the collecting channels.

The present invention also provides methods of use of the shunt devices.One embodiment of the present invention is directed to a surgical methodto divert aqueous humor from the anterior chamber of the eye intoSchlemm's canal with a device that is implanted to extend from withinthe anterior chamber to Schlemm's canal. The portion of the deviceextending into Schlemm's canal can be fashioned from a flexible materialcapable of being received within a portion of the radius, curvature, anddiameter of Schlemm's canal. All or parts of the device may be solid,porous, tubular, trough-like, fenestrated, or pre-curved.

One embodiment of the present invention is illustrated in FIG. 1A, inwhich the shunt device 100 is shown in a side view. The shunt device 100of this embodiment is comprised of two portions, a proximal portion 10which joins a distal portion 25. The proximal portion 10 and distalportion 25 shown create an enclosed tubular channeling structure. Thetotal length of the distal portion 25 may be between about 1 and 40 mm,preferably about 6 mm. The same embodiment of the present invention isillustrated with phantom lines showing the internal fluid communicationpath in FIG. 1B. The lumen or channeling space defined by the walls ofthe proximal portion 10 and the distal portion(s) 25 are continuous attheir junction at the distal portion portal 20.

An alternate embodiment of the present invention is shown in FIG. 1C, inwhich the shunt device 100 is comprised of two luminal mesh elements,with a proximal portion 10 which joins a distal portion 25. Yet anotherembodiment of the present invention is shown in FIG. 1D, in which theshunt device 100 is comprised of two solid, porous elements which mayprovide wick-like fluid communication therethrough, with a proximalportion 10 which joins a distal portion 25.

An alternate embodiment of the present invention is shown in FIG. 1E, inwhich the shunt device 100 is comprised of a proximal portion 10 havingtwo lumens therein terminating in proximal portion portals 18. Thedistal portion 25 shaped and sized to be received within Schlemm's canalextends in either direction having separate lumens traversingtherethrough from each of the distal portion portals 20.

Other examples of embodiments of the present invention are shown inFIGS. 2-5D. FIG. 2 shows an embodiment of the inventive shunt in whichthe device 100 is tubular and fenestrated (15, 30) in its configuration,with an acute (<90) angle of junction between the proximal portion 10and the plane defined by the distal portion 25. Such fenestrations (15,30) may be placed along any portion of the device 100 to facilitate thepassage of fluid therethrough, but are particularly directed towards thecollecting channels of the eye. FIG. 2 further shows an alternateembodiment of the present invention in which the terminal aspect 16 ofthe proximal portion is angulated toward the iris 40 with respect to themain axis of the proximal portion 10, with the portal 18 of the proximalportion directed toward the iris 40. In alternate embodiments as shownin FIG. 6C, the portal 18 of the proximal portion 16 is directed awayfrom the iris 40.

FIG. 3A shows an embodiment of the inventive shunt in which a portion ofthe channeling device is enclosed and tubular in configuration at thejunction of the proximal portion 10 and the distal portion 25, but wherethe distal portion 10 is a trough-like channel. The distal portionportal 20 is also shown. The invention contemplates that any portion ofthe device 100 can be semi-tubular, open and trough-like, or a wick-likeextension. Tubular channels can be round, ovoid, or any other enclosedgeometry. Preferably the non-tubular trough-like aspects are orientedposteriorly on the outer wall of the canal to facilitate aqueous humordrainage to the collecting channels of the eye, as shown in FIG. 3A.

FIG. 3B shows an overhead view of the embodiment of the inventive shuntof FIG. 3A, further detailing the relationship among the proximalportion 10 and the distal portion 25. The aqueous humor directingchannel is shown in dashed lines. FIG. 3C shows a proximal view of theembodiment of the inventive shunt of FIG. 3A, further detailing therelationship among the proximal portion 10 and the distal portion 25.

FIG. 3D shows another embodiment of the inventive shunt in which thestructure of the device 100 comprises an aqueous humor directing channelthat is both open and curved in a continuous trough-like configurationalong the proximal portion 10 and the distal portion 25. The distalportion portal 20 is also an open trough-like channel.

FIG. 4 shows another embodiment of the inventive shunt with the additionof aqueous humor-wicking extensions 32 which are either continuous with,or attached to the terminal aspects of the distal portion 25. Thewicking extensions 32 can be fashioned from a monofilament or braidedpolymer, such as proline, and preferably have a length of 1.0 mm to 16.0mm. Furthermore, the proximal portion 10 is curved with a sealed,blunted tip 16 and contains a portal 18 in fluid communication with thelumen of the proximal portion and oriented to face away from the iriswhen the shunt device 100 is implanted in its intended anatomicposition. The shunt device 100 can also help to maintain the patency ofSchlemm's canal in a stenting fashion.

FIG. 5A shows another embodiment of the inventive shunt in which theproximal portion 10 joins a single, curved distal portion 25 in a“V-shaped,” tubular configuration. The embodiment shown in FIG. 5A canalso have a portal (not shown) in the distal portion 25 adjacent to thejunction with the proximal portion 10 in order to facilitatebi-directional flow of fluid within the canal. Fenestrations andnon-tubular, trough-like terminal openings are contemplated in allembodiments of the invention, and these fenestrations and openings maybe round, ovoid, or other shapes as needed for optimum aqueous humorchanneling function within the anatomic spaces involved.

FIG. 5B shows another embodiment of the inventive shunt in which thebody or device 100 comprises only a single, curved distal portion 25which contains a distal portion portal 20 oriented towards the anteriorchamber to allow egress of aqueous humor from the anterior chamber toSchlemm's canal. The body of this device can have a length of about 1.0mm to 40 mm, preferably about 6 mm. The external diameter can be about0.1 mm to 0.5 mm, or about 0.3 mm.

FIG. 5C shows another embodiment of the inventive shunt in which thedevice 100 comprises a bi-directional tubular distal portion 25 which isintersected by a proximal portion 10 which is short in length relativeto the distal portion 25 and is directed towards the anterior chamber.

FIG. 5D shows still another embodiment of the inventive shunt in whichthe device 100 comprises a bi-directional, trough-like, curved distalportion 25 for insertion into Schlemm's canal, which contains a distalportion portal 20 oriented to allow egress of aqueous humor from theanterior chamber, wherein the trough-like distal portion 25 is orientedto open toward the collecting channels to facilitate the egress ofaqueous humor.

FIG. 5E shows another embodiment of the inventive shunt in which thedevice 100 comprises a bi-directional, solid distal portion 25 forinsertion into Schlemm's canal to facilitate the egress of aqueous humorfrom the canal to the collecting channels in a wicking capacity. Thesolid distal portion 25 can be porous or non-porous.

As the inventive device is an implant, it can be fabricated from amaterial that will be compatible with the tissues and fluids with whichit is in contact. It is preferable that the device not be absorbed,corroded, or otherwise structurally compromised during its in situtenure. Moreover, it is equally important that the eye tissues and theaqueous remain non-detrimentally affected by the presence of theimplanted device. A number of materials are available to meet theengineering and medical specifications for the shunts. In the exemplaryembodiments of the present invention, the shunt device 100 isconstructed of a biologically inert, flexible material such as siliconeor similar polymers. Alternate materials might include, but are notlimited to, thin-walled Teflon, polypropylene, other polymers orplastics, metals, or some combination of these materials. The shuntdevice 100 may be constructed as either porous or solid in alternateembodiments. The material can contain a therapeutic agent deliverable tothe adjacent tissues.

In the embodiments shown in FIGS. 1-4, the proximal portion 10 joins thedistal portion(s) 25 at an angle sufficient to allow the placement ofthe proximal portion 15 within the anterior chamber of the eye when thedistal portion 25 is oriented in the plane of Schlemm's canal. Theproximal portion 10 is preferably of sufficient length, about 0.1 to 3.0mm or about 2.0 mm, to extend from its junction with the distal portion25 in Schlemm's canal towards the adjacent space of the anteriorchamber. While many geometries can be used for channeling aqueous humor,the diameter or width of the proximal portion 10 can be sized to yieldan internal diameter of between about 0.1 and 0.5 mm, preferably 0.20mm, for a tubular or curved shunt, or a comparable maximal width for ashunt with a multiangular configuration. In other embodiments, theproximal portion is a non-luminal, non-trough-like wicking extensionthat provides an aqueous humor directing channel along the lengththereof.

Because the nature of the iris 40 is such that it tends to comprise aplurality of rather flaccid fimbriae of tissue, it is desirable to avoidsaid fimbriae from being drawn into the lumen of an implant, thusoccluding the shunt device. Therefore, the proximal portion 10 maycontain a plurality of fenestrations to allow fluid ingress, arranged toprevent occlusion by the adjacent iris. Alternately, the proximalportion 10 may comprise only a proximal portion portal 18 in the form ofa fenestration oriented anteriorly to provide continuous fluid egressbetween the anterior chamber of the eye and the directing channel of theshunt. Said fenestrations may be any functional size, and circular ornon-circular in various embodiments of the present invention. Inaddition, a porous structural material can assist in channeling aqueoushumor, while minimizing the potential for intake of fimbriae.

Furthermore, the proximal portion 10 may be positioned sufficientlyremote from the iris 40 to prevent interference therewith such as bytraversing a more anterior aspect of the trabecular meshwork into theperipheral corneal tissue. In yet another possible embodiment, as shownin FIG. 6C, the device 100 may comprise a proximal portion 10 in whichthe terminal aspect of said proximal portion. 10 is curved or angledtoward the iris 40, and with a, blunted, sealed tip 16 and a portal 18oriented anteriorly to face away from the underlying iris 40. Such aconfiguration would tend to decrease the possibility of occlusion of theshunt device by the iris 40.

The device 100 may contain one or more unidirectional valves to preventbackflow into the anterior chamber from Schlemm's canal. The internallumen for an enclosed portion of the device or the internal channeldefined by the edges of an open portion of the device communicatesdirectly with the inner lumen or channel of the distal portion at theproximal portion portal 20.

The distal portion 25 may have a pre-formed curve to approximate the 6.0mm radius of Schlemm's canal in a human eye. Such a pre-formed curvatureis not required when flexible material is used to construct the shuntdevice 100. The distal portion 25 may be of sufficient length to extendfrom the junction with the proximal portion 10 through any length of theentire circumference of Schlemm's canal. Embodiments having a distalportion 25 that extends in either direction within Schlemm's canal canextend in each direction about 1.0 mm to 20 mm, or about 3.0 mm, topermit circumferential placement through Schlemm's canal. The diameterof width of the distal portion 25 can be sized to yield an outerdiameter of between about 0.1 and 0.5 mm, or about 0.3 mm, for a tubularor curved shunt, or a comparable maximal width for a shunt with amultiangular configuration. The distal portion 25 may contain aplurality of fenestrations to allow fluid egress, arranged to preventocclusion by the adjacent walls of Schlemm's canal. In otherembodiments, the distal portion is a non-luminal, non-trough-likewicking extension that provides an aqueous humor directing channel alongthe length thereof.

In the exemplary embodiments of the present invention, the shunt devicemay be either bi-directional, with the distal portion of the implantintersecting with the proximal portion in a “T-shaped” junction as shownin FIGS. 1A-1E, 2, 3A-3D, 4 and 5C, or uni-directional, with a“V-shaped” junction of the proximal and distal shunt portions, as shownin FIG. 5A. A bi-directional shunt device can have a distal portion thatis threaded into opposing directions within Schlemm's canal. In the caseof the uni-directional shunt, only the distal shunt portion is placedwithin Schlemm's canal. In these exemplary embodiments, “non-linearfluid communication” means that at least some portion of the shuntthrough which fluid passes is not in a straight line. Examples ofnon-linear shunts are the above described bi-directional “T” shapes, andthe uni-directional “V” shapes, or shunts having two channel openingswhich are not in straight alignment with each other.

The surgical anatomy relevant to the present invention is illustrated inFIG. 6A. Generally, FIG. 6A shows the anterior chamber 35, Schlemm'scanal 30, the iris 40, cornea 45, trabecular meshwork 50, collectingchannels 55, episcleral veins 60, pupil 65, and lens 70. FIG. 6Billustrates the surgical placement of the exemplary embodiment of thepresent invention, with the relevant anatomic relationships. It shouldbe noted that the inventive device is designed so that placement of thedistal portion 25 within Schlemm's canal 30 results in an orientation ofthe proximal portion 10 within the anterior chamber 35 within the angledefined by the iris 40 and the inner surface of the cornea 45.Therefore, if the plane defined by Schlemm's canal is defined as zerodegrees, the proximal portion 10 can extend therefrom at an angle ofbetween about +60 degrees towards the cornea 45 or −30 degrees towardthe iris 40, more preferably in the range of 0 to +45 degrees. Thisrange may vary in individuals having a slightly different location ofSchlemm's canal 30 relative to the limbal angle of the anterior chamber35.

In yet another embodiment of the present invention not shown, the shuntdevice 100 is configured with one distal portion 25 which is tubular toprovide a shunting functionality and a plurality of proximal portions 10which provide an anchoring function to stabilize the overall implantdevice, in addition to providing fluid communication from the anteriorchamber to Schlemm's Canal.

The surgical procedure necessary to insert the device requires anapproach through a conjunctival flap. A partial thickness scleral flapis then created and dissected half-thickness into clear cornea. Theposterior aspect of Schlemm's canal is identified and the canal isentered posteriorly. The anterior chamber may be deepened with injectionof a viscoelastic and a miotic agent. The proximal portion of the shuntis then inserted through the inner wall of Schlemm's canal andtrabecular meshwork into the anterior chamber within the angle betweenthe iris and the cornea. In some cases, as incision may be needed fromSchlemm's canal through the trabecular meshwork into the anteriorchamber to facilitate passage of the proximal portion therethrough. Onearm of the distal portion of the shunt device is grasped and threadedinto Schlemm's canal. In a similar fashion, the other arm of the distalportion of the shunt device (when present) is inserted into Schlemm'scanal in the opposing direction from the first. The scleral flap andconjunctival wound are closed in a conventional manner.

While the above-described embodiments are exemplary, the inventioncontemplates a wide variety of shapes and configurations of the shunt toprovide fluid communication between the anterior chamber and Schlemm'scanal. The above-described embodiments are therefore not intended to belimiting to the scope of the claims and equivalents thereof.

1. An implant for treating glaucoma, comprising: a body beingbiocompatible when implanted, said body comprising: a flow passage ofsufficient length to extend from an anterior chamber of an eye into aphysiologic outflow path of the eye; an inlet section sized and shapedto be disposed in the anterior chamber; and an outlet section shaped tobe disposed in the physiologic outflow path and having a cross-sectionaldimension within the range of about 0.1 mm to about 0.5 mm so as to fitwithin the physiologic outflow path, and having a plurality of outletsto drain into the physiologic outflow path.
 2. The implant of claim 1,wherein the body is configured such that, when the implant is positionedwithin the eye, fluid flows from the anterior chamber through at leastone inlet of the inlet section and into the outlets.
 3. The implant ofclaim 1, wherein the body further comprises an anchor portion forstabilizing the body relative to the physiologic outflow path.
 4. Theimplant of claim 3, wherein at least one of the outlets is disposed onthe anchor portion.
 5. The implant of claim 1, wherein the body furthercomprises a terminal aspect angulated to extend away from the iris. 6.The implant of claim 1, wherein at least a portion of the implant iscomprised of a solid material.
 7. The implant of claim 1, wherein atleast a portion of the implant comprises a mesh material.
 8. The implantof claim 1, wherein at least a portion of the implant is fenestrated. 9.The implant of claim 1, wherein the implant generally has a T-shape. 10.The implant of claim 1, wherein the outlet section is configured to bedisposed within Schlemm's canal.
 11. The implant of claim 1, wherein thelength of the portion of the body extending from the anterior chamber tothe physiologic outflow path is about 2.0 mm.
 12. The implant of claim1, wherein the body further comprises an intermediate section betweenthe inlet and outlet sections of sufficient length to extend throughtissue between the anterior chamber and the physiologic outflow path.13. The implant of claim 12, wherein the inlet, intermediate and outletsections comprise a substantially continuous tubular structure.
 14. Theimplant of claim 12, wherein the inlet and intermediate sections have acombined length within the range of about 0.1 mm to about 3 mm.
 15. Theimplant of claim 14, wherein the combined length of the inlet andintermediate sections is about 2 mm.
 16. The implant of claim 1, whereinthe inlet and outlet sections comprise a substantially continuoustubular structure.
 17. The implant of claim 1, wherein the body has amulti-angular configuration.
 18. The implant of claim 1, wherein thecross-sectional dimension of the outlet section is about 0.3 mm.
 19. Theimplant of claim 1, wherein the outlet section has a length within therange of about 1 mm to about 40 mm.
 20. The implant of claim 19, whereinthe length of the outlet section is about 6 mm.
 21. The implant of claim1, wherein the outlet section has a pre-formed curve with a radius ofabout 6 mm.
 22. The implant of claim 1, wherein the flow passagecomprises a channel.
 23. The implant of claim 22, wherein the channelcomprises a lumen.
 24. The implant of claim 23, wherein at least aportion of the lumen has a diameter or width within the range of about0.1 mm to about 0.5 mm.
 25. The implant of claim 24, wherein at least aportion of the lumen has a diameter or width of about 0.2 mm.
 26. Animplant for treating glaucoma, comprising: a body being biocompatiblewhen implanted, said body comprising: an inlet section sized and shapedto be disposed in an anterior chamber of an eye, the inlet sectionhaving at least one inlet; an outlet section shaped to be disposed in aphysiologic outflow path of the eye and having a cross-sectionaldimension within the range of about 0.1 mm to about 0.5 mm so as to fitwithin the physiologic outflow path, and having a plurality of outletsto be disposed in the physiologic outflow path; and a flow passageextending through the body from the inlet to the plurality of outlets.27. The implant of claim 26 , wherein the body further comprises ananchor portion for stabilizing the body relative to the physiologicoutflow path.
 28. The implant of claim 27, wherein at least one of theoutlets is disposed on the anchor portion.
 29. The implant of claim 26,wherein the outlet section is configured to be disposed within Schlemm'scanal.
 30. The implant of claim 29, wherein the flow passage divergesinto at least two branches within the outlet section.
 31. The implant ofclaim 30, wherein each of the at least two branches within the outletsection extend outward from a section of the flow passage in a directionsubstantially perpendicular to the section of the flow passage.
 32. Theimplant of claim 31, wherein the at least two branches extend inopposite directions.
 33. The implant of claim 26, wherein the bodyfurther comprises an intermediate section between the inlet and outletsections of sufficient length to extend through tissue between theanterior chamber and the physiologic outflow path.
 34. The implant ofclaim 33, wherein the inlet, intermediate and outlet sections comprise asubstantially continuous tubular structure.
 35. The implant of claim 33,wherein the inlet and intermediate sections have a combined lengthwithin the range of about 0.1 mm to about 3 mm.
 36. The implant of claim35, wherein the combined length of the inlet and intermediate sectionsis about 2 mm.
 37. The implant of claim 26, wherein the inlet and outletsections comprise a substantially continuous tubular structure.
 38. Theimplant of claim 26, wherein the body has a multi-angular configuration.39. The implant of claim 26, wherein the cross-sectional dimension ofthe outlet section is about 0.3 mm.
 40. The implant of claim 26, whereinthe outlet section has a length within the range of about 1 mm to about40 mm.
 41. The implant of claim 40, wherein the length of the outletsection is about 6 mm.
 42. The implant of claim 26, wherein the outletsection has a pre-formed curve with a radius of about 6 mm.
 43. Theimplant of claim 26, wherein the flow passage comprises a channel. 44.The implant of claim 43, wherein the channel comprises a lumen.
 45. Theimplant of claim 44, wherein at least a portion of the lumen has adiameter or width within the range of about 0.1 mm to about 0.5 mm. 46.The implant of claim 45, wherein at least a portion of the lumen has adiameter or width of about 0.2 mm.